I've got 2 pullets, maybe 14 days old or so, who get dirty butts. I've been washing them off, but the poo is not clearing the tail when they poop. It's normal when they poop, just clings to the feathers and then dries. I've been watching them. In the morning, if I see it's there and don't clean it up, they're the same when I get home and clean them later. At what point do I just watch and wait, not cleaning them, if there is such a time? They're in a big area--18' by 20' carport that's fenced in with sand as the floor and straw scattered about, and they're hard to catch. I wonder, too, about their age because all of the 10 chicks rarely go under the heat lamp, preferring to burrow under the straw. I can go out in the night, low 40's, and not see them at all and then, around first light, they come out from under the pile of straw and go play. Only wispy tails at this point and hardly anything I'd call feathers, but don't mind the cool air.